(1) Field of the Invention
The present invention relates to conduits for fluid flow and is directed more particularly to a conduit for flowing electrically conductive fluid.
(2) Description of the Prior Art
Attempts to reduce flow friction in a pipe have been numerous and varied, and have included additives to the fluid and/or pipe, coating on the pipe, and deformable pipe surfaces. Other approaches have involved the use of mechanical oscillations of the pipe to introduce width-wise or span-wise, force which have been shown to enhance channel flow. However, mechanical oscillations are impractical in most flow situations and require moving parts.
U.S. Pat. No. 4,824,329 to Yamamoto et al. provides an apparatus for controlling the flow of a liquid metal through a conduit. The flow path is located where a magnetic field perpendicularly intersects an electric current and the flow path perpendicularly intersects both the magnetic field and the electric current. The interaction of the electric and magnetic field creates a force parallel to the flow direction so as to apply a braking force to the flow. The electric properties of the fluid vary with temperature such that the braking force is controlled by the temperature of the liquid. As the force is directed parallel to the flow, the device serves essentially as a pump controlling the rate of flow. The device does not reduce flow friction except as related to flow rate.
U.S. Pat. No. 5,437,421 to Nosenchuck et al. provides a complex array of electromagnetic tiles over a surface to control the boundary layer of a fluid traveling over the surface. Each tile generates magnetic and electric fields in the fluid near the surface such that each tile can produce a force normal to the surface. The electric and/or magnetic fields of each tile are individually controlled such that the forces can be made to act separately. The force at each tile is timed to act in opposition to the boundary layer microturbulent flow over the tile to thus smooth the flow and reduce surface drag. The complex tile arrangement and control lends itself to flow over an open surface as the tiles could not be readily applied to the inside of a conduit.
There is a need for a fluid conduit wherein wall friction is reduced by span-wise perturbations which are not mechanically induced.